suggest assert wide_int larger than hashval_t

[Jay K]

It's "just" a warning, no "real" affects seen.
I patched my copy to say
  hwi = ((hwi >> (shift - 1)) >> 1);

Thanks,
 - Jay

----------------------------------------
> From: iant@google.com
> To: jay.krell@cornell.edu
> CC: gcc@gcc.gnu.org
> Subject: Re: suggest assert wide_int larger than hashval_t
> Date: Mon, 19 Jul 2010 00:36:06 -0700
>
> Jay K  writes:
>
> > I get this in 4.3.5:
> >
> > ../../gcc/gcc/varasm.c: In function `const_rtx_hash_1':
> > ../../gcc/gcc/varasm.c:3387: warning: right shift count >= width of type
> >
> > ./include/hashtab.h:typedef unsigned int hashval_t;
> >
> >   unsigned HOST_WIDE_INT hwi;
> >   hashval_t h, *hp;
> >  ...
> >     const int shift = sizeof (hashval_t) * CHAR_BIT;
> >     const int n = sizeof (HOST_WIDE_INT) / sizeof (hashval_t);
> >     int i;
> >
> >     h ^= (hashval_t) hwi;
> >     for (i = 1; i < n; ++i)
> >       {
> >         hwi >>= shift;  here
>
> It's not an actual problem, because the code is never executed in the
> case where right shift count >= width of type. Note that the loop
> starts at 1. If this is breaking bootstrap that it needs to be
> addressed one way or another, otherwise it's not too serious.
>
> Ian